Skeleton King's revival upon death proved too destructive. For the Wraith-Night solstice, players must await Skeleton King's rebirth to become the Wraith King. For this winter update, Valve removed Skeleton King from the DOTA 2 roster until players collect enough souls to bring about the birth of the Wraith King.
When players protect Skeleton King's grave from the onslaught on enemies, players can collect Phantom Fragments. Using these fragments, players can exchange them for different tiers of Wraith-Night Reliquaries, which award limited time items.
The update brings a new character to the DOTA 2 roster and introduces the Legion Commander. The armored legion excels in head-to-head combat. Her Duel ability locks her and another enemy in one-on-one fight, where the surviving hero gains a permanent damage increase. Her other abilities include counter-attack for lifesteal, remove debuffs from an ally and provides movement speed bonuses from an AOE attack.
The update also brings ranked matchmaking much sooner than expected. Valve detailed the ranked matchmaking process, but did not reveal a release date. The ranked matchmaking now comes part of today's update and promises to balance matches for a fair challenge for all players.
The update brings new changes to the core game as well. Some changes include a Hand of Midas recipe increase, option for minimap position and general bug fixes.
You can read about the entire DOTA 2 update here.